Scharpfenecker Marion, Kruse Jacqueline J C M, Sprong Debbie, Russell Nicola S, Ten Dijke Peter, Stewart Fiona A
Department of Experimental Therapy, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
Int J Radiat Oncol Biol Phys. 2009 Feb 1;73(2):506-13. doi: 10.1016/j.ijrobp.2008.09.052.
Transforming growth factor-beta (TGF-beta) and Notch signaling pathways are important regulators of vascular homeostasis and vessel remodeling; mutations in these pathways can lead to vascular disorders. Similar vascular phenotypes develop in the normal tissues of cancer patients as a long-term effect of radiotherapy. Irradiation most severely affects the capillaries, which become leaky and dilated and might eventually rupture. To investigate the mechanism of such capillary damage, we studied the effect of TGF-beta and Notch signaling in microvascular endothelial cells.
Human microvascular endothelial cells were irradiated with 5 or 10 Gy and activation of TGF-beta and Notch signaling pathways was assessed by biochemical methods and a cell migration assay.
Ionizing radiation induced Smad2 phosphorylation and nuclear translocation and increased mRNA and protein expression of the activin-like kinase 5 (ALK5) target gene plasminogen activator inhibitor-1 (PAI-1). At the same time, we observed diminished Smad1/5/8 activation and downregulation of the ALK1 downstream target, inhibitor of DNA binding-1 (ID-1). We also measured an upregulation of the Notch ligand Jagged-1 and the target gene Hey1. Decreased inhibitor of DNA binding-1 levels coincided with a reduced ability of the cells to migrate.
Ionizing radiation shifts the balance from ALK1 to ALK5 signaling and activates the Notch pathway in endothelial cells. This combination of anti-angiogenic signals contributes to reduced cell migration after irradiation.
转化生长因子-β（TGF-β）和Notch信号通路是血管稳态和血管重塑的重要调节因子；这些通路中的突变可导致血管疾病。作为放疗的长期影响，癌症患者的正常组织中会出现类似的血管表型。辐射对毛细血管影响最为严重，毛细血管会变得渗漏、扩张，最终可能破裂。为了研究这种毛细血管损伤的机制，我们研究了TGF-β和Notch信号在微血管内皮细胞中的作用。
用人微血管内皮细胞接受5或10 Gy的辐射，并通过生化方法和细胞迁移试验评估TGF-β和Notch信号通路的激活情况。
电离辐射诱导Smad2磷酸化和核转位，并增加激活素样激酶5（ALK5）靶基因纤溶酶原激活物抑制剂-1（PAI-1）的mRNA和蛋白质表达。同时，我们观察到Smad1/5/8激活减少以及ALK1下游靶标DNA结合抑制剂-1（ID-1）下调。我们还检测到Notch配体Jagged-1和靶基因Hey1上调。DNA结合抑制剂-1水平降低与细胞迁移能力下降一致。
电离辐射使内皮细胞中的信号传导从ALK1向ALK5转变，并激活Notch通路。这种抗血管生成信号的组合导致辐射后细胞迁移减少。
